Esters of substituted phenoxyphthalic acids

ABSTRACT

ESTERS OF PHENOXYPHTHALIC ACID ARE OBTAINED WHEN ALKALI METAL SALTS OR ALKALINE EARTH METAL SALTS OF HYDROXYPHTHALIC ACIDS ESTERS ARE REACTED IN A POLAR ORGANIC SOLVENT, AT TEMPERATURES OF BETWEEN 50 AND 200*C., WITH DERIVATIVES OF BENZENE WHICH ARE BOTH HALOGENATED AND SUBSTITUTED BY ELECTROPHILIC RADICALS. THE END PRODUCTS PREPARED IN THIS WAY MAY BE USED AS MOLLUSCICIDES. THE DIMETHYL ESTER OF 4&#39;&#39;-NITRO-4-PHENOXY-PHTHALIC ACID IS PARTICULARLY SUITABLE FOR THIS PURPOSE. MOREOVER, THE PRODUCT OF THIS INVENTION CAN BE USED AS PLASTICIZERS FOR POLYVINYCHLORIDE AND SIMILAR PLASTICS.

United Smtes 3,686,266 ESTERS F SUBSTITUTED PHENOXY- PHTHALIC ACIDS Heinz Gilch, Krefeld, and Hermann Schnell, Krefeld- Urdingeu, Germany, assignors to Farbeufabriken Bayer Aktiengesellschaft, Leverlrusen, Germany No Drawing. Filed July 18, 1968, Ser. No. 745,707 Claims priority, appliclga tigsrggrmany, July 26, 1967,

Int. Cl. C071: 121/66 US. Cl. 260-465 D 2 Claims ABSTRACT OF THE DISCLOSURE Esters of phenoxyphthalic acid are obtained when alkali metal salts or alkaline earth metal salts of hydroxyphthalic acid esters are reacted in a polar organic solvent, at temperatures of between 50 and 200 C., with derivatives of benzene which are both halogenated and substituted by electrophilic radicals. The end products prepared in this way may be used as molluscicides. The dimethyl ester of 4'-nitro-4-phenoxy-phthalic acid is particularly suitable for this purpose. Moreover, the product of this invention can be used as plasticizers for polyvinylchloride and similar plastics.

-COOR COOR' In this formula, R and R denote any aliphatic or aromatic hydrocarbon radical which may be the same or different, and they preferably represent alkyl radicals with 1 to 6 carbon atoms. If the alkali metal salts or alkaline earth metal salts of these compounds are used in this invention, the OH group is replaced by MeO, Me denoting an alkali metal or an alkaline earth metal, preferably sodium or potassium. Examples of these compounds are dimethyl 4'hydroxyphthalate, diethyl-3-hydroxyphthalate and their sodium or potassium salts.

l-lalogenated benzene derivatives which may be used include compounds of the general formula in which X denotes a halogen atom, preferably chlorine, and R denotes an electrophilic radical, preferably N0 CN, COOR (R =alkyl, aryl), 50 R or COR. R is preferably an alkyl radical having 1 to 6 carbon atoms or an aryl radical e.g. phenyl and naphthyl. The electron attracting radical is defined as a radical which has a s p-value according to the Hammet equation greater than 0.20. X is preferably in the por o-position to R Examples of these compounds are: p-nitrochlorobenzene, o-nitrofluorobenzene, p-cyanochlorobenzene and p- 3,686,266 Patented Aug. 22, 1972 fiuorobenzophenone; chloroand fluoronitrobenzene are particularly suitable.

The end products obtained correspond to the formula in which R, R and R have the meanings indicated above.

Examples of phenoxyphthalic acid esters obtained by the process according to the invention are dimethyl 4- nitro-4-phenoxy-phthalate, diethyl 2'-nitro 3 phenoxyphthalate, dimethyl 4'-cyano-4-phenoxy-phthalate and diethyl 4'-benzoyl-4-phenoxy-phthalate.

Solvents in which the process may be carried out include organic solvents such as dimethylsulphone, dimethylsulphoxide, dimethylformamide and acetonitrile. Dimethylsulphoxide is particularly suitable.

The process is usually carried out by first reacting a hydroxyphthalic acid ester, dissolved in an inert organic solvent such as toluene or benzene, with an aqueous alkali metal hydroxide or an alkali metal alcoholate or an alkali metal to form the corresponding alkali metal salt. Instead of alkali metal compounds, alkaline earth metal compounds may be used. Preferably, sodium or sodium compounds are used. The resulting alkali metal salt or alkaline earth metal salt of the hydroxyphthalic acid ester is then reacted with the halogenated benzene in one of the aforesaid polar solvents. This reaction is generally carried out at 50 to 200 C. This stage is preferably carried out with the complete exclusion of water. The water formed during the reaction is distilled off azeotropically together with the organic solvent which is then returned to the reaction system after removal of the water.

The completion of the reaction can be detected by the neutral reaction of the reaction mixture. The end products can be isolated from this mixture by removal, for example from the alkali metal halide or alkaline earth metal halide formed in the reaction, by filtration. The remaining solution can then be concentrated by evaporation.

The end products prepared in this way may be used as molluscicides. The dimethyl ester of 4'-nitro-4-phen0xyphthalic acid is particularly suitable for this purpose.

The products of this invention can also be used as plasticizers for polyvinylchloride and similar plastics. They may be incorporated e.g. on a crew extruder as is usual with incorporating additives in plastics and may be used in amounts of from 5 to 50% by weight, preferably 10 to 20% by weight. These additives exert the same plasticizing effect as normally used phthalic acid esters. Their main advantage is in the fact that the substituent on the aromatic nucleus reduces their migration so that plastics which contain the products of this invention as plasticizers especially polyvinylchloride will not give off these additives in the course of time.

The instant compounds are also intermediates for producing coating materials, such as lacquers and films, resistant to high temperatures, as disclosed and claimed in copending US. application Ser. No. 745,401, filed July 17, 1968, now Pat. No. 3,503,928.

The use of the instant intermediates may be appreciated from the following further example:

58 g. of the dimethyl ester of 4-nitro-4-phenoxy-phthalic acid are dissolved in 116 ml. of methanol and hydrogenerated in the presence of Raney nickel at 70 C. in a vibratory autoclave. After removal of the catalyst, the solution is concentrated by evaporation and the residue is recrystallised from methanol. Yield 46 g. of 4'-amino-4- phenoxyphthalic acid dimethylester, M.P. 93-94" C.

Analysis-Calculated (percent): C, 63.8; H, 4.6; O, 26.6; N, 5.0; Found (percent): C, 63.5; H, 4.7; 0, 26.6; N, 4.8.

The dimethyl ester of 4-amino-4-phenoxyphthalic acid is saponified in a methanolic solution of potassium hydroxide under refiux in an atomsphere of nitrogen. The hydrochloride of 4'-amino-4-phenoxyphthalic acid is prepared by introducing the methanolic solution dropwise into a mixture of 50% water and 50% concentrated hydrochloric acid, and it is then recrystallised from water. 5 g. of the hydrochloride of 4'-amino-4-phenoxyphthalic acid are suspended in purified thionyl chloride at room temperature and stirred until no further evolution of gas can be observed (6 to 8 hours). The thionyl chloride is re moved by evaporation and the chloride of 4'ammonium- 4-phenoxy-phthalic acid anhydride remaining behind is dissolved in 25 ml. of anhydrous pyridine without further purification and stirred for 4 hours at 25 C. A viscous solution is obtained which is divided into two halves. One half is poured on a glass plate and heated under nitrogen, first at 150 C. for one hour and then at 300 C. for 30 minutes. The resulting film can withstand temperatures above 400 C. without visible damage. The second half of the solution is introduced dropwise into dilute acetic acid and the resulting precipitate of polyamidocarboxylic acid is filtered off, washed with methanol and water and dried under vacuum. The product can be stored for some time in this form. 1 g. of the polyamidocarboxylic acid is dissolved in 4 ml. of dimethyl formamide and converted as described above into a polyimide film which has the same properties. Heat distortion temperature: 560 C.

EXAMPLE 1 Preparation of the dimethyl ester of 4-(4-nitrophenoxy)-phthalic acid:

21.2 g. (0.1 mol) of dimethyl 4-hydroxyphthalic acid are dissolved in 100 ml. of toluene. 2.3 g. (0.1 mol) of sodium are dissolved in 50 ml. of methanol and combined with the toluene solution. The methanol is distilled off with most of the toluene, and after the addition of a solution of 17.5 g. (0.1 mol) of p-chloronitrobenzene in 100 ml. of dimethylsulphoxide, it is heated under reflux in an atmosphere of nitrogen, reflux being carried out over a water separator. After 3 hours the reaction mixture is neutral. The sodium chloride formed is filtered off and the solvent is distilled ofi under a water jet vacuum. The

residue is recrystallised from methanol. M.P. 85-87" C. Yield 27 g.

The structure is confirmed by the IR and NMR spectra. Elementary analysis.-Calculated (percent): 58.0, C; 3.9, H; 33.8, 0; 4.2 N. Found (percent): 58.1, C; 3.8, H; 32.1, 0; 4.4, N.

EXAMPLE 2 Example 1 was repeated using a solution of 4.0 g. (0.1 mol) of sodium hydroxide in 10 ml. of water in place of the sodium methylate. The water was distilled off azeotropically with toluene, and the solution of p-chlorom'trobenzene was then added. Yield: 25 g.

We claim:

1. Phenoxyphthalic acid esters of the formula -O00RI R' -ooo in which R is N0 CN, COOR, R or COR, R and R are alkyl of l to 6 carbon atoms or phenyl radicals, and

R* is alkyl of 1 to 6 carbon atoms, phenyl or naphthyl.

2. Phenoxyphthalic acid esters according to claim 1 wherein R and R are alkyl radicals having 1 to 6 carbon atoms.

References Cited UNITED STATES PATENTS 6/1914 Ostermann 2606l2 R LORRAINE A. WEINBERGER, Primary Examiner J. F. TERAPANE, Assistant Examiner US. Cl. X.R.

Patent No. 3 6 D ted August 2 1972 Invcntor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 4, line 15, Claim 1 "COO" should be (100R Signed and sealed this 9th day of January 1973.,

(SEAL) Attest; EDWARD M.FLB'1CIHR :JR. ROBERT (FOTTSCHALK Commissioner of Patents Attesting Officer 

